I. Field of the Invention
This invention relates generally to pulse rate control of a portable entertainment device, and more particularly to a system for controlling the playing of a radio or an audio or video cassette used during physical exercise so that the device will play only if the person's heart rate lies within a preset frequency band.
II. Discussion of the Prior Art
While undergoing a course of exercise, it has become quite popular for the person involved to listen to music or other audio entertainment through earphones connected to a radio receiver/audio cassette player or while watching a video cassette or broadcast exercise programs on T.V. The music or other programming helps to alleviate the boredom which often accompanies an extended period of physical exercise. Thus, one commonly sees joggers, bikers, aerobic dancers, etc. wearing earphones or watching T.V. while exercising.
It is also well known that for a program of exercise to be effective, it must be sufficiently strenuous to produce a heart rate above some lower threshold but below a preset upper threshold. Between these two thresholds is a so-called "window of exercise". If the exercise produces heart rates below the lower threshold then, it is not particularly useful to the cardiopulmonary system. On the other hand, if the exercise is so strenuous that the heart rate exceeds an upper threshold, then the exercise may be placing too great a strain on the system and could cause negative results. The thresholds, of course, are unique to the particular person undergoing the exercise program and depend, for example, on age, weight, the condition of the cardiovascular system, etc.
A variety of devices are on the market for indicating heart rate during the course of exercise. Certain of these devices also provide an alarm if and when the exercise is resulting in a person's heart rate falling outside of the window. One such device is the ET 2000 which is manufactured and sold by Cardio Systems, Inc. of Eden Prairie, Minn. In the case of the ET 2000, electrodes are placed on the chest and conductive leads exceed from those electrodes to an electronic module worn typically on the wrist. Contained within the electronic module is a microprocessor which is programmed to coact with a suitable LED or LCD readout to provide a digital indication of the heart rate being sensed. The device also includes a keypad whereby the upper and lower limits can be programmed into the device. In addition to the digital readout, it also includes a tone generator for producing an audible signal if and when the upper rate limit is exceeded.